A crayon containing a colorant, an organic solvent, a resin and a gelling agent as main components has been conventionally well known, and in particular, a crayon obtained by using a benzylidene sorbitol gelling agent is in wide use as it is practically excellent. Such a crayon that is obtained by using a benzylidene sorbitol gelling agent is prepared by a process, for example, which involves adding a resin component and a coloring agent to an appropriate organic solvent and dissolving or dispersing them therein to prepare a solution, adding thereto a benzylidene sorbitol gelling agent and dissolving it therein under heating to prepare a raw material solution, pouring the solution into a cylindrical molding container, for example, and then cooling and gelling (solidifying) the same (see Patent Literature 1).
In such a process for producing a crayon as mentioned above, when carbon black is used as a coloring agent, poor gelation frequently occurs in a final gelling process, resulting in that a crayon cannot be stably produced. More specifically, carbon black and a resin component are dispersed and dissolved, respectively, in an organic solvent, a benzylidene sorbitol gelling agent is dissolved in the resultant solution under heating to prepare a raw material solution, the raw material solution is poured into a molding container, depending on the case, while continuously heating the raw material solution so that the gelling agent remains dissolved in the raw material solution, and when the solution is cooled and solidified, it frequently happens that the gelling agent does not function, resulting in poor gelation.
When poor gelation occurs on the occasion of pouring the obtained raw material solution into a molding container, the crayon obtained does not have a desired hardness. Accordingly, the crayon is easy to collapse in writing, resulting in difficulty of writing. Depending on the case, the raw material solution does not gel, and thus a crayon cannot be obtained.
Patent Literature 1: Japanese Patent Publication No. 54-23619